Magnetic separator



May 30, 1939.

P. L. STEFFENSEN 2,160,628

MAGNETIC SEPARATOR Filed March 3, 1937 3 Sheets-Sheet. 2

y 1939- P. L. STEFFENSEN .1 5

MAGNETIC SEPARATOR Filed March 3, 193"! 3 Sheets-Sheet 3 BL. saw/25m;

Patented May 30, 1939 UNITED STATES MAGNETIC SEPARATOB Percy Lea Steffensen, Cornwall, Pa., assignor to Bethlehem Steel Company, a corporation of Pennsylvania Application March a. 1031. Serial No. 128.743

21 Claims.

This invention relates to improvements in apparatus,and method for the magnetic separation of pulverized was such as'shown in Patent No. 946,394.

5 Magnetic separators oi the. above'mentioned type are arranged with electro-magnets suspended in a flxed but adjustable position inside a closed revolving non-magnetic drum in such a position that the pole pieces are close tothe inside bottom 0! the drum. The feed. a mixture of water and solids, enters onesidev of a box in which the bottom outsidesurface oi the drum is in close proximity to the surface of the liquid, and passes over a bridge or wier located approximately at the vertlcal-center line oi the drum at a short distance from the outside bottom surface of the In passing over the bridge or wier, the feed is brought within the ileld o! the magnets inside of the drum and consequentiv the magnetic particles contained in the feed are attracted to and retained on the surface of the revolving drum, which carries them. forward separating them from the non-magnetic material in the food. when using a separator ,5 of this type it has become customary to employ two or more drums arranged in series to retreat the concentrates in order to obtain a satisfactory product.

I have modified and improved this arrange- 3o mentso as to provide for treating finely 'ground feed. and obtaining in a single drum unit a clean concentrate and tailings very low in magnetic aiaterial, thus obtaining a highly eihcient operaon. 1 In this new type separator, which I have devised. the feed is introduced into the-'hottom of the feed boxclose to the'vertical axis of the drum under sufficient hydraulic, head to cause the feed pulp to flow freely upward and through 4 the magnetic-field of the machine without settling outsolids. I have found thatan inlet six inches to one foot above the ieveloi' the tailing overflow is suilleient under ordinary operating conditions. actual head automatically addusts itself, de nding on the character and volume. of feed and on the resistance to. flow thro'u'ghthe machine.

The feed iiows upwardly toward the drum and through a narrow. passageway in an elongated m stream around thedrum-to the tailings overncw wier in a direction opposite the the drum. The ma netic material picked up bythe drum is carried along as it revolves in passing from pole to pole oi the magnets, the reversal of polarity oi the poles causes the magnetic parti- (0!. soc-214) cles to move among themselves in the well known I manner.

The rotation of the drum carries the concentrates away from. the tailings discharge to the other side of the machine into a shallow concen- 5 trate discharge passage up and out of the magnetic field where they drop of! or are washed oi! the surface of the drum with water sprays onto a discharge chute. Fresh water is supplied under slight pressure to the concentrate disl0 charge passage counter-current to the movement of the concentrates for thoroughly washing the concentrates and diluting and replacing slime which may be carried with the concentrates. The wash water then mixes with the fresh feed tor further treatment.

The novel features will be more fully understood from the following description and claims taken with the drawings, in. which:

' Fig. l is a sectional view taken on line i--i 20 of Fig,,3.

Fig.1 is a sectional view taken on line 2-2 of Fig. 1.

Fig. 3 is a sectional view taken on line 3'-3 of Fig. 1.

Fig. 4' is a sectional view taken on line 4-4 of Fig. 3.

In the drawings. 1 is a supporting structure for the horizontal shaft 2. on which is revolved in the-direction of the arrow a hollow drum I of 0 non-magnetic material. Upon this shaft is secured. within the drum. a series of stationary electromagnets 4 so that they may be adjusted rotarily relative to the drum by means of lever I. The magnet shoes 6 have a spread of approx- 35 imately 110, of which, about constitutes the initial pick-up field, and the remaining constituting the washing field for the concentrates. The actual magnetic iield, however. is somewhat greater than the spread of the shoes. It will be 40 ,noted that the bottom portion-of the drum is merged in the bath for about of its cir- -mlerence,v all oiwhich is within the magnetic id of the shoes thus materially contributing to the high eiiiciency of the separator. Under '45 thedrumlsateedboxl..'lheteed,amixture of water and nno solids .into which the drum 'dipaenters one side oi thebox by meansolconduit I which introduces the feed into the bot-1 iomoitheboxtliroughopeningltoavertical 50 chamber il' having a restricted opening llat itsupperendlocatedclosetothemtical centerline oftheliruin. The vertical portion it of the feed conduitbeing of sutlcient heightso as to produce a hydraulicmead on the fluid in the II box thus causing the feed to flow freely upward through a curved pick-up pe ll of considerable length formed by the surface of the drum and plate M to the tailings overflow or wier II into launder l8, hence through openings II for disposal.

It will be noted that the outward flow of fluid through passage I3 is in counterdirection to the rotation of the drum. The dimensions of this passage may vary with different conditions oi feed pulp. The passage extends through about of the periphery of the drum, all of which is within the magnetic field. This relatively long time in the magnetic field provides ample opportunity for the magnetic material to be very com-;

pletely removed from the feed.

The magnetic material picked up by the magnets and held against the surface of the.drum is carried along by the drum as it revolves, and in passing from pole to pole of the magnets the reversal of polarity of the poles causes the magnetic particles to move among themselves. This movement allows non-magnetic material to drop out. A certain amount of magnetic or weakly magnetic material may fall 011 but before this can escape with the tailings, it must pass through the pick-up passage with new feed where it will again be picked up by the magnets and carried along with the concentrates. This arrangement in combination with only one outlet for tailings and that within or just beyond the magnetic field and only slightly below the concentrates discharge level It is an important feature of this separator as it largely prevents loss of magnetic material in the tailings.

In some previous types of separators .part of the tailings are discharged through spigots at the bottom of the box. Any magnetic or weakly magnetic material which escapes from 'the magnetic field will pass through the spigots and v be lost in the tailings since the spigots are beyond the magnetic field.

Therotation of the drum carries the concentrates away from the tailings overflow Ii to .more fresh water boxes "-24 to which fresh water is suppliedunder slight pressure. Openings 2526 are provided between the edges of the plates for directing the water downwardly into discharge passage is in counter-current to the movement of the concentrates carried through the same passage by the drum. This countercurrent flow of fresh water provides for thoroughly washing the concentrates, the fresh water diluting and replacing slime which may be carried with the concentrates. During this final washing, there is, of course, a tendency to wash of! some of the magnetic particles but these particles have ample opportunity to be again picked up, combined with new feed, before being lost in the tailings. Fresh water is supplied to compartments ll, 23 and 16 through inlets i1, 28 and 29, respectively. These compartments are defined by the'side walls 8. and II of the box and partitions 32 and ll with bottom 34 and end walls 38.

A guard plate It over the tailings overflow wier i5 prevents concentrates, which may be carried over the top of the drum, from falling into the tailings, as it will direct them into the magnetic field and again be picked up by the drum.

Branch pipes II are provided for injecting water under pressure into the bottom 0! chamber Ill so as to dislodge solids which might settle out of the feed pulp and thereby plug up the feed. This is used only when such a condition occurs.

While I have described the separator using a drum and magnets of the Grondal type, the principle of operation could also be used in any other form of wet magnetic separator which would permit the introduction 0! feed at some intermediate point in the magnetic held; the discharge of the tailings in one direction after the stream has passed through a part of the magnetic field counter-current to a means for con veying the magnetic material pulled out of the stream by the magnets; and the discharge of the magnetic material beyond the magnetic field onthe opposite side fromthe tailings discharge and at an elevation only slightly higher than the tailings overflow level, after the concentrates have. been thoroughly washed with clear water while still inthe magnetic field. The mixing of the wash water with the incoming fresh feed renders this method of sepa ation highly eilicient because all dislodged mate al picked up in the washing operation undergoes repeated separation which cuts down magnetic loss in the tailings. By my method of separation, a clean and highly concentrated recovery may be effected in but one operation, in contrast to the two cycle separation commonly used.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In a magnetic separator, the combination with a feed box, of a rotatable drum mounted in said box, a feed chamber for conducting feed to the bottom of the drum, means for supplying feed to said chamber, a tailings overflow positioned above and to one side of said chamber, a concentrates discharge positioned above and at the opposite side of said chamber, and passageways formed by portions of the drum and the box communicating with said chamber and said overflow and discharge.

2. In a magnetic separator. the combination with a feed box, of a rotatable drum mounted in said box, a feed chamber having a vertical dis-' charge opening close to the bottom of the drum, means for supplying feed to said chamber under hydraulic head, a tailings overflow positioned above and in spaced relation to said opening, a concentrates discharge positioned above and at the opposite side of said overflow, and narrow passageways formed by portions of the drum and the box communicating with said opening and said overflow and discharge.

3. In a magnetic separator, the combination with a feed box, of a rotaaible drum mounted in said box, a vertical feed chamber having a discharge opening in close proximity to the bottom of said drum, 0. tailings overflow positioned above and in spaced relation to said opening, a concentrates discharge positioned above and at the opposite side, of the box relativeto said overflow, an elongated passageway on each side of said chamber formedibyportions oi. the drum and theboxcommunicatihgwithsaidchamberand means for forming a pick-up passageway and a concentrates discharge passageway under the drum ,on respective opposite sides of said feed chamber and communicating therewith, means for supplying i'eed under hydraulic head to said chamber, and means for supplying fresh water under slight pressure to the concentrates discharge passageway in counter-current to the movement of the concentrates for washing same.

5. In a magnetic separator, the combination with a feed box, of a drum rotatably mounted in said box, a feed chamber having a discharge opening positioned close to the bottom of the drum. a tailings overflow positioned above and to one side of said chamber, a concentrates discharge positioned above said overflow but on the opposite side of said chamber, an elongated passageway on each side of said chamber formed by portions oi. the drum and box communicating with said chamber and said overflow and concentrates discharge, means for supplying feed to said chamber so as to cause an upward flow of feed through one of said passages and over the tailings overflow, means for rotating the drum counter to said flow, means for supplying fresh water under slight pressure to the other passageway in counter-current to the movement of the drum, and a guard positioned over the taillngs overflow close to said drum for preventing concentrates falling into the tailings.

6. In a magnetic separator, the combination with a feed box, of a rotatable drum mounted in said box, a vertical feed chamber having a discharge opening positioned close to the bottom 01 the drum, means for supplying feed under pressure to the bottom of said chamber, a tailings overflow positioned above and in spaced relation to said opening, a non-magnetic plate for bridging the space between said opening and said overflow and in spaced relation to the outside surface of the drum, a concentrates discharge at theother side oi the box relative to said overflow, a non-magnetic plate. bridging the space between said concentrates discharge and said teed opening and in closely spaced relation to the outside surface of the drum, 9. water box under said last mentioned plate, an opening through said plate, and means, for supplying water to said box and to said i'eed chamber.

7. In a magnetic separator, a feed box, a rotatably mounted drum partially submerged in the feed contained in said box, angularly adjustable ilxed magnets within said drum, an elongated pick-up passage under said drum and within the field oi said magnets and terminating in a taiiings overflowat one side of the box, an elongated concentrates discharge passage under said drum opposite said overflow, said concentrates passage being within the magnetic field, means for producing a flow of teed through said pick-up passage around said drum in counterdirection to the direction of rotation 01' said drum, and means for supplying a stream 0! wash water to said con centrates discharge passage in counterdirection to the rotation 01 said drum.

8. In a magnetic separator, a feed box, s rotatably mounted drum partially submerged in. the feed contained in said box, fixed means adjustably mounted within said drum for producing a magnetic field outside of said drum, means for producing an upward flow of feed around and elm to the bottom surface of said drum through less than one half oi said magnetic field and in a direction opposite to the direction of travel of the bottom 01 said drum to a taiiings overflow whereby concentrates are picked up and carried by the drum, a narrow passage around and close to the bottom surface of said drum extending through the remaining portion 01' said magnetic field and through which the concentrates carried by the drum must pass, means for washing said concentrates in their travel through said passage, means for removing substantially all of said concentrates from the drum alter emerging from said passage, and means for preventing concentrates not removed from the drum from escaping with the tailinss.

9. In a magnetic separator, a series of stationary magnets associated with each other to produce a fixed magnetic field, successive sections of which have opposite polarity, a conveyor cooperable directly with the poles of said magnets and movable through said field to move a thin layer of mixed magnetic and non-magnetic particles along said field, a feed box containing a bath of ieed'pulp within which one end portion of said field is disposed substantially at the surface level of said bath and the other end of said field being disposed above said level, means for introducing said feed at a point intermediate of said field and causing same to flow in an elongated stream opposite to the movement of said conveyor, means for removing magnetic particles at one end of said field in the direction of travel of said conveyor,-means for removing non-magnetic particles at the other end of said field in counter direction of travel of said conveyor, and means for washing said magnetic particles before removal from said bath.

10. In a magnetic separator, a series of angularly adjustable, stationary magnets associated with each other to produce a fixed magnetic field, successive sections of which have opposite polarity, a conveyor cooperable directly with the poles of said magnets and movable through said field to move a thin layer of mixed magnetic and non-magnetic particles along said field, a feed box containing a bath of feed pulp within which one end portion of said field is disposed substantially at the surface level oi said bath and the other end or said field being disposed above said level, said conveyor contacting said bath for substantially 25 per centoi its periphery. means for introducing feed at the lowest point of said conveyor and causing same to flow around substantially 12 per cent of the effective surface of said conveyor in a thin stream, means for removing magnetic particles at one end of said field in the direction of travel oi said conveyor, means for discharging non-magnetic particles at the opposite end of said field-in counter direction of travel of said conveyor, means for washing said magnetic particlesbeiore removal from said bath, and means for mixing said wash with fresh feed at its point of initial contact with said conveyor.

11. In a magnetic separator, a series of angularly adjustable, stationary magnets associated with each other to produce a tiled masnetlc field,

successive sections of which have opposite polarity, a drum cooperable directly with the poles of said magnets and movable hrough said field to convey a thin layer of mixed magnetic and nonmagnetic particles along said field, a feed box containing a bath of feed pulp within which one end portion of said field is disposed substantially at the surlace level of said bath and the other end of said field being disposed above said level, said drum being submerged in said bath for substantially 90 degrees of its circumference, means for supplying feed to said drum at its lowest point and causing same to fiow upwardly and around substantially 45 degrees of its efiectivesurface, means for removing magnetic particles atone end of said field in the direction of rotation of said drum, means for discharging non-magnetic particles at the opposite end of said field in counter direction of rotation of said drum, means for washing magnetic material carried by said drum with a thin stream of water before said material is removed from said bath, and means for introducing said wash water into fresh feed adjacent the point where the feed first contacts the drum.

12. The method-oi separating magnetic material from non-magnetic material, comprising producing a feed pulp of water and solids to be treated, passing said feed through a magnetic zone so as to separate the magnetic material from the non-magnetic material, collecting the separated magnetic material on a moving body and disposing of the non-magnetic material contained in said feed, removing the separated magnetic material from the zone of separation in concentrated form to another magnetic zone; passing said concentrates through a shallow stream of fresh wash water flowing in a direction opposite to the travel of said concentrates, then removing the concentrates from the magnetic zone and returning the magnetic material separated from the concentrates during the washing operation directly to the first separating zone and out of contact with the previously treated non-magnetic material for subsequent recovery.

13; The method of separating magnetic material from non-magnetic material, comprising producing a feed pulp of water and solids to be treated, flowing said feed through a magnetic zone so as to separate the magnetic material from the non-magnetic material, collecting the separated magnetic material on a non-magnetic m'ov ing body passing through said field and disposing of the non-magnetic material contained in said reed, moving the collected magnetic material in concentrated form to another portion of said magnetic zone in which the concentrates are washed by a shallow stream of fresh water flowing counter to the movement of the concentrates, then removing the washed concentrates from'the magnetic zone and flowing said wash water uncontaminated by contact with the previously treated non-magnetic material directly to the first separating zone for recovery of the magnetic material contained in said wash water.

14. The method of efficiently separating magnetic material from non-magnetic material in a single operation, comprising producing a feed pulp of water and solids to be treated, flowing said feed through a magnetic field of fixed range so as to induce separation of the magnetic material from the feed, concentrating the separated magnetic material on the surface of a non-magnetic moving body passing through said field and disposing of the tailings at the feed end of said field. moving the collected material to another portion of said field in which the concentrates are washed with fresh water flowing in counter direction to the movement of the concentrates and in an elongated stream held in intimate contact with said moving body, flowing said wash water uncontaminated by contact with the previously treated non-magnetic material to the initial field of separation for recovery of magnetic particles carried in said water, and removing the washed concentrates from the washing stream for final recovery.

15. The method of separating magnetic material from non-magnetic material, comprising producing a feed pulp of water and finely ground material to be treated, flowing saidleed through a magnetic field so as to induce separation of the magnetic material from the non-magnetic material, collecting the magnetic material on a non-magnetic body moving through said field. disposing of the greater portion of the non-magnetic material produced by said separation in the form of fluid tailings, moving the collected magnetic material in concentrated form to another portion of said field and washing the concentrates by an elongated stream of fresh water flowing counter to the movement of the concentrate and in intimate contact therewith, mixing said wash water uncontaminated by contact with the previously treated non-magnetic material with fresh feed for further separation of magnetic material contained in the wash, and removing the washed concentrates from said washing stream for final recovery at the end of the magnetic field.

16. The method of separating magnetic material from non-magnetic material in a single operation, comprising producing a feed pulp of water and solids to be treated, flowing said feed through a pick-up zone of a magnetic field for effecting separation of the magnetic material from thenon-magnetic material and collecting the magnetic material on a moving body passing through said field, disposing of the non-magnetic material separated from the magnetic material, transferring said magnetic material to another zone of said field devoted principally to a washlng operation, washing the magnetic material with fresh water in said second zone and introducing said wash water uncontaminated by contact with the previously treated feed directly into said pick-up zone for-further treatment in combination with fresh feed, and removing the washed magnetic material from the magnetic field for final recovery.

17. The method of separating magnetic material from non-magnetic material, comprising providing a feed pulp'of water and solids to be treated, flowing said feed pulp through a zone in a magnetic-field in a shallow, elongated path thereby-separating the magnetic material from the non-magnetic inaterial, collecting the magnetic material on a body moving through said magnetic field, disposing of the material not so collected, transferring said magnetic material into another zone in said field; washing said magnetic material with fresh water in said other zone, removing the washed magnetic material and transferring the wash water out of contact with the previously treated non-magnetic material to the first mentioned zone for further magnetic separation treatment.

18. The method of separating magnetic material from non-magnetic material, comprising providing a feed pulp of water and solids to be treated, introducing said feed pulp into a magnetic field at a point intermediate the ends of said field, flowing said pulp towards one end of said field, separating the magnetic material from the non-magnetic material, collecting the separated magnetic material on a body moving through said magnetic field in a direction opposite to the flow of the pulp, moving the collected magnetic materiai into another portion of said magnetic field, washing said collected magnetic material by means of a stream 01' water flowing in a direction opposite to that of the collected magnetic material and flowing the wash water out of contact with the previously treated nonmagnetic material into the stream of feed pulp for further magnetic treatment.

19. In a magnetic separator, the combination with a feed box, of a rotatable drum mounted in said box, means for creating a'magnetic field upon'the bottom of said drum, a feed chamber for conducting feed to the bottom of the drum, means for supplying feed to said chamber, a tailings overflow positioned above and to one side of said chamber, a concentrates discharge positioned above and at the opposite side of said chamber, and passageways formed by portions of the drum and the box communicating with said chamber and said overflow and discharge.

20. In a magnetic se arator, the combination with a feed box, of conveying means mounted in said box, a feed chamber for conducting feed to the bottom of the conveying means, means for supplying feed to said chamber, a tailings overflow positioned above and to one side of said chamber, a concentrates discharge positioned above and to oneside of said chamber, a concentrates discharge positioned above and at the opposite side of said chamber, and passageways formed by portions of the conveying means and the box communicating with said chamber and said overflow and discharge.

21. In an apparatus for separating materials, the combination with a feed box, of a rotatable drum mounted in said box, means associated with said drum for separating the desired material from' the refuse associated therewith, a feed chamber for conducting feed to the bottom of the drum, means for supplying feed to said chamber, an overflow for refuse positioned above and to one side of said chamber, a discharge for the desired material positioned above and at the opposite side of said chamber, and passageways formed by portions of the drum and the box communicating with said chamber and said overflow and discharge.

PERCY LEA STEFFENSEN.

CERTIFICATE OF CORRECTION.

Patent No. 2,160,628.

may 5 PERCY LEA STEFFENSEN.

It is hereby certified that error appears in the printed specification of the above'numbered patent requiring correction as follows: Page 5, sec- 0nd column, lines 6and'-?, claim 20, strike out'the words andbomma "a concentrates discharge positioned above and tonne side of said chamber}; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this hth day of July, A. D. 1939.

(Seal) Henry Van Arsdale Acting Commissioner of Patents.

netic field at a point intermediate the ends of said field, flowing said pulp towards one end of said field, separating the magnetic material from the non-magnetic material, collecting the separated magnetic material on a body moving through said magnetic field in a direction opposite to the flow of the pulp, moving the collected magnetic materiai into another portion of said magnetic field, washing said collected magnetic material by means of a stream 01' water flowing in a direction opposite to that of the collected magnetic material and flowing the wash water out of contact with the previously treated nonmagnetic material into the stream of feed pulp for further magnetic treatment.

19. In a magnetic separator, the combination with a feed box, of a rotatable drum mounted in said box, means for creating a'magnetic field upon'the bottom of said drum, a feed chamber for conducting feed to the bottom of the drum, means for supplying feed to said chamber, a tailings overflow positioned above and to one side of said chamber, a concentrates discharge positioned above and at the opposite side of said chamber, and passageways formed by portions of the drum and the box communicating with said chamber and said overflow and discharge.

20. In a magnetic se arator, the combination with a feed box, of conveying means mounted in said box, a feed chamber for conducting feed to the bottom of the conveying means, means for supplying feed to said chamber, a tailings overflow positioned above and to one side of said chamber, a concentrates discharge positioned above and to oneside of said chamber, a concentrates discharge positioned above and at the opposite side of said chamber, and passageways formed by portions of the conveying means and the box communicating with said chamber and said overflow and discharge.

21. In an apparatus for separating materials, the combination with a feed box, of a rotatable drum mounted in said box, means associated with said drum for separating the desired material from' the refuse associated therewith, a feed chamber for conducting feed to the bottom of the drum, means for supplying feed to said chamber, an overflow for refuse positioned above and to one side of said chamber, a discharge for the desired material positioned above and at the opposite side of said chamber, and passageways formed by portions of the drum and the box communicating with said chamber and said overflow and discharge.

PERCY LEA STEFFENSEN.

CERTIFICATE OF CORRECTION.

Patent No. 2,160,628.

may 5 PERCY LEA STEFFENSEN.

It is hereby certified that error appears in the printed specification of the above'numbered patent requiring correction as follows: Page 5, sec- 0nd column, lines 6and'-?, claim 20, strike out'the words andbomma "a concentrates discharge positioned above and tonne side of said chamber}; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this hth day of July, A. D. 1939.

(Seal) Henry Van Arsdale Acting Commissioner of Patents. 

